Recreating Flawed Ammunition

[lamarbrog]

This idea has been pestering me a little recently, and I wanted to explore it with you guys and see where it leads us.

Knowing what we know now about cleaning and lubrication in the AR platform (particularly lubrication) I have been wondering just how negative of an impact the ball powder that slipped into early ammunition production really was. Many other changes were made at around the same time... and, based on my knowledge, it is not 100% clear to me that the rifle, given the more modern mechanical improvements and lubricants, could not function reliably with ball powder.

Has anyone tried to recreate the flawed ammunition and run a comparison of the two? If not, if I can acquire the information to recreate it I might be interested in doing a casual test of this come spring. I have a reloading press and .223Rem dies... Would just have to acquire components.

What are the thoughts on this?

[Paulo_Santos]

What powder did they use back then?

[lamarbrog]

The story I have heard was that, in an attempt to save money by not wasting material, they formulated a load that used existing stocks of ball powder for the 7.62NATO. Apparently it has a slower burn rate than what is typically used for the 5.56NATO, and leaves more residue.

[Paulo_Santos]

The root cause of the stoppages turned out to be a problem with the powder for the ammunition. In 1964 when the Army was informed that DuPont could not mass-produce the nitrocellulose-based powder to the specifications demanded by the M16, the Olin Mathieson Company provided a high-performance ball propellant of nitrocellulose and nitroglycerin. While the Olin WC 846 powder was capable of firing an M16 5.56*mm round at the desired 3,300*ft (1,000*m) per second, it had the unintended consequence of increasing the automatic rate of fire from 850 to 1000 rounds per minute. This would leave behind dirty residue, making the M16 more likely to have a stoppage. The problem was resolved by fitting the M16 with a buffer system, slowing the rate of fire back down to 650 to 850 rounds per minute and outfitting all newly produced M16s with an anti corrosive chrome-plated chamber.[30]

This is what I found on it.

[lamarbrog]

Where did you source this information...

I'm not saying it is totally wrong... but it differs in some aspects from what I have heard, and some things don't really make sense to me. (However, I am not a reloader or a student of internal ballistics, so this may just be due to ignorance.)

I guess where I am left off... is it doesn't mention what powder replaced that. Are we still using this "dirty" powder?

Also, if it propels the bullet at approximately the same velocity, that leads me to believe (possibly incorrectly) that it is generating approximately the same pressure. So... What would cause the cyclic rate to increase 150rpm? Is the pressure peaking at a different point causing increased pressure in the gas tube?



I know this probably is boring to a lot of folks... "They fixed it, what does it matter?" I guess this is just my little exploration into "Weapon Evolution: History Detectives"... explore the past of the platform's evolution, and we might learn something that could help us now.

[Paulo_Santos]

I got it from Wikipedia. The 55 and 62 GR ammo uses WC 844 powder, which is a little faster than WC 846. This link has some info:
http://www.gun-shots.net/ballistics-chart.shtml

[lamarbrog]

http://www.thegunzone.com/556prop.html
(http://www.thegunzone.com/556prop.html)

I found this little article that is pretty interesting... Had to read it twice to keep up with all the numbers, but I think I understand it.

What I am reading this as meaning...

IMR4475 seems to be the "original" powder, which was not a ball power... however, it was originally used in .30-06. I guess my inference from prior information would be that this powder functioned well, but did not provide adequate velocity without exceeding chamber pressure specs.

It looks to me like WC844 and WC846 were originally one powder type, known as WC846, a ball powder used in 7.62NATO. The issue came down to the specs for WC846 being too loose, so they basically divided it into two different powders which filled different segments of the original spec.

So, tell me if I am wrong but....
Conclusion
IMR4475 functions, but fails to achieve specified velocity.
Original-Spec WC846 worked sometimes, and not others, due to too much variation in the powder.
WC844 is the same powder as WC846, but with stricter specifications so as to eliminate the "bad" lots of WC846.

So, really, the change to ball powder was not the problem, and we continue to use it today. The problem was using ball powder with too varied of tolerances?

[Paulo_Santos]

Sounds correct.

[lamarbrog]

Well, I guess that doesn't really leave much to test... Still interesting to explore the history a little.

I wonder what the chances are that a better powder is available now for use in M193/M855 but what we are using is "good enough" so we don't change?

[Paulo_Santos]

There is new powders from Alliant and Hodgdon coming out for us reloaders that will safely produce top velocities. I'm going to see which ones work better for the 5.56.

[lamarbrog]

Sounds intriguing. I look forward to seeing what results you get.